Cationic polymer

Abstract

PCT No. PCT/US95/14679 Sec. 371 Date Jul. 10, 1997 Sec. 102(e) Date Jul. 10, 1997 PCT Filed Nov. 13, 1995 PCT Pub. No. WO96/15154 PCT Pub. Date May 23, 1996The invention relates to a cationic polysaccharide, preferably in fibrous form, having superabsorbent characteristics. The polysaccharides are substituted by quaternary ammonium groups, have a ds of at least 0.5, preferably 0.5 to 2.5 and are cross-linked to a sufficient extent that it remains insufficient in water. The polysaccharide is preferably cellulose. An increased number of functional groups in the product improves superabsorbent properties, whereas use of a cross-linking agent makes it possible to control the gel strength of the product and makes it easier to tailor the characteristics of the product to those which are required.

We claim: 
     
       1. A cationic polysaccharide having superabsorbent characteristics, the polysaccharide being substituted by quaternary ammonium groups and having a ds of at least 0.5, and the polysaccharide being cross-linked to a sufficient extent that it remains insoluble in water. 
     
     
       2. The cationic polysaccharide according to claim 1 wherein the polysaccharide is cellulose. 
     
     
       3. The cationic polysaccharide according to claim 1 in fibrous form. 
     
     
       4. The cationic polysaccharide according to claim 1 wherein the quaternary ammonium groups are derived from a quaternary ammonium compound of one of the general formulae (I) and (II): ##STR4## wherein n is an integer from 1 to 16; X is halogen;   Z -  is an inorganic or organic anion;   R, R 1 , R 2  and R 3 , which may be the same or different are each hydrogen or an organic radical; or additionally R 2  may represent a group of formula (III) or (IV): ##STR5## in which p is an integer from 2 to 10; and   n, R, R 1 , R 2 , R 3  X and Z are as defined above.   
     
     
       5. The cationic polysaccharide according to claim 4 wherein each of R, R 1 , R 2  and R 3  is hydrogen or an alkyl, hydroxyalkyl, alkenyl or aryl group containing up to 10 carbon atoms. 
     
     
       6. The cationic polysaccharide according to claim 5 wherein each of R, R 1 , R 2  and R 3  is hydrogen. 
     
     
       7. The cationic polysaccharide according to claim 6 wherein the quaternary ammonium compound is selected from: glycidyltrimethylammonium chloride;   2,3-epoxypropyl-N,N,N-trimethylammonium chloride;   3-chloro-2-hydroxypropyl-N,N,N-trimethylammonium chloride;   3-chloro-2-hydroxypropyl-N,N,N-dimethylethanolammonium chloride; and   1,3-bis-(3-chloro-2-hydroxypropyl-N,N-dimethylammonium)-N-propane dichloride.   
     
     
       8. The cationic polysaccharide according to any of claim 1 wherein the cross-linking agent is a diepoxy compound or a haloepoxy compound. 
     
     
       9. The cationic polysaccharide according to claim 8 wherein the cross-linking agent is 1,3-bis(glycidyl dimethylammonium)propane dichloride or epichlorohydrin. 
     
     
       10. The cationic polysaccharide according to claim 1 having a ds of from 0.5 to 2.5. 
     
     
       11. A process for the production of a cationic polysaccharide having superabsorption characteristics which comprises: (i) reacting a polysaccharide with an excess of a quaternary ammonium compound containing at least one group capable of reacting with polysaccharide hydroxyl groups to provide a polysaccharide with a ds of at least 0.5; and simultaneously or subsequently   (ii) reacting the derivatised polysaccharide with a cross-linking agent to provide a degree of cross-linking sufficient that the product remains insoluble in water.   
     
     
       12. The process according to claim 11 wherein the polysaccharide is cellulose. 
     
     
       13. The process according to claim 11 wherein the polysaccharide is a fibrous polysaccharide. 
     
     
       14. The process according to claim 11 wherein the quaternary ammonium compound is a compound of one of the general formulae (I) and (II): ##STR6## wherein n is an integer from 1 to 16; X is halogen;   Z -  is an inorganic or organic anion;   R, R 1 , R 2  and R 3 , which may be the same or different are each hydrogen or an organic radical; or additionally R 2  may represent a group of formula (III) or (IV): ##STR7## in which p is an integer from 2 to 10; and   n, R, R 1 , R 2 , R 3  X and Z are as defined above.   
     
     
       15. The process according to claim 14 wherein each of R, R 1 , R 2  and R 3  is hydrogen or an alkyl, hydroxyalkyl, alkenyl or aryl group containing up to 10 carbon atoms. 
     
     
       16. The process according to claim 15 wherein each of R, R 1 , R 2  and R 3  is hydrogen. 
     
     
       17. The process according to claim 16 wherein the quaternary ammonium compound is selected from: glycidyltrimethylammonium chloride;   2,3-epoxypropyl-N,N,N-trimethylammonium chloride;   3-chloro-2-hydroxypropyl-N,N,N-trimethylammonium chloride;   3-chloro-2-hydroxypropyl-N,N,N-dimethylethanolammonium chloride; and   1,3-bis-(3-chloro-2-hydroxypropyl-N,N-dimethylammonium)-N-propane dichloride.   
     
     
       18. The process as claimed in claim 11 wherein the cross-linking agent is a diepoxy compound or a haloepoxy compound. 
     
     
       19. The process as claimed in claim 18 wherein the cross-linking agent is 1,3-bis(glycidyl dimethylammonium)propane dichloride or epichlorohydrin. 
     
     
       20. The process as claimed in claim 11 wherein step (ii) is carried out subsequently to step (i). 
     
     
       21. The process as claimed in claim 11 wherein the quaternary ammonium compound is used in a molar ratio based on saccharide units in the polysaccharide of 5:1 to 40:1, or wherein the reaction is carried out in two or more steps and a molar ratio of 10:1 to 20:1 applied in each step. 
     
     
       22. The process as claimed in claim 11 wherein derivatisation and cross-linking reactions are carried out in the presence of base. 
     
     
       23. The process as claimed in claim 22 wherein the base is an alkaline earth metal hydroxide or alkoxide. 
     
     
       24. The process as claimed in claim 23 wherein the base is sodium hydroxide. 
     
     
       25. A method of absorbing a liquid which comprises of introducing the cationic polysaccharide of claim 1 to a liquid to be absorbed. 
     
     
       26. The method according to claim 25, wherein the cationic polysaccharide is incorporated as an absorbent in a hygiene and/or sanitary article.